Variable Responses of Seedlings of Two Wheat Cultivars towards Exogenous Hydrogen Peroxide

Aims: Recent reports have shown that hydrogen peroxide (H2O2) is an important signaling molecule and that interacts with abscisic acid (ABA) signalling for some of its physiological effects.

Study Design: This work was conducted to study H2O2 regulation of seed germination, growth and antioxidant potential in two wheat cultivars varying in drought tolerance and ABA-sensitivity. Sodium tungstate as ABA biosynthetic inhibitor was used to evaluate the effects of H2O2 mediated through ABA biosynthesis.

Place and Duration of Study: Laboratory of Department of Biochemistry, Punjab Agricultural University, Ludhiana, 141004 India, between June 2012 and September 2012.

Methodology: Two wheat cultivars C306 (ABA higher sensitive and drought tolerant) and PBW343 (ABA lesser sensitive and drought susceptible) were used. 50 mM H2O2 with and without sodium tungstate (an inhibitor for ABA biosynthesis) was supplied exogenously for 24-48 h to 4-day old seedlings. Data was taken at 24 and 48 h after treatment.

Results: Exogenous H2O2 delayed germination in both cultivars. It increased shoot and root biomass in C306 but not in PBW343. It increased antioxidant potential in terms of increased activities of antioxidant enzymes and proline contents in both cultivars but such increases were significantly higher in C306. It also led to production of some level of oxidative stress in terms of increased contents of H2O2, malondialdehyde (MDA), and decreased levels of ascorbate contents and ascorbate/dehydroascorbate ratio in both cultivars but level of such oxidative stress was higher in PBW343. These H2O2-regulated effects were affected by inhibiting ABA biosynthesis in both cultivars; however, the effects were higher in C306 as compared to PBW343.

Conclusion: H2O2-regulations were higher in wheat cultivar C 306 than PBW 343. Such regulations were partly mediated through ABA biosynthesis.